1) Field of the Invention
The present invention relates to electromagnets and, more particularly, to an electromagnet having a spacer that defines channels that facilitate cooling of the electromagnet, as well as an associated apparatus and method.
2) Description of Related Art
Electromagnets are used for various purposes, such as in motors, generators, solenoids, back-up power systems, and transformers. One common application for electromagnets is to provide the actuator mechanism during the installation of rivets or other fasteners, such as in large airframe structures including wing skins, fuselage skins, and the like. Additionally, electromagnets can be used to clamp multiple structures together while drilling or performing a tooling operation on the clamped structures, thereby resulting in a burr-less and debris-free hole. Similarly, an electromagnet may be used to clamp structures together while inserting a rivet or similar fastener to attach the structures. Clamping generally occurs when an electromagnet is positioned adjacent to a structure, and a ferrous material is positioned on the other side of the structure to create a clamping force between the electromagnet and ferrous material.
In most basic principles, the electrical energy input to an electromagnet creates mechanical energy output. Electromagnets generally comprise a coil and ferromagnetic core. The coil generally surrounds the core. As a current is passed through the coil, a magnetic field is created in the vicinity, and the core becomes magnetized and attracts any magnetic material. The force of the magnetic field can be adjusted by changing the number of windings comprising the coil or the amount of current applied to the coil. Electromagnets may be classified as either DC (direct-current) or AC (alternating current), and the type of core depends on which type of current is provided. In either case, as DC or AC is applied to the coil, resistive losses in the coil lead to heat production. As heat increases, methods for cooling the coil become necessary to remove the excess heat and assure consistent performance. Generally, forced convection and water-cooling are methods used to cool electromagnets.
Specifically, some electromagnet coils are cooled by using a hollow winding and then circulating fluid through the winding. This technique requires high current power supplies and powerful pumps to drive the fluid through a long, narrow passageway. Another technique is bathing the coil in a fluid to conduct heat from the coil to the fluid. Alternatively, layers of the coil may be separated by spacers to facilitate fluid flow, as is most commonly used with large transformers for utility power equipment. The spacers used with electrical utilities are commonly stacked lengthwise along the core and are typically large (about 12 inches in diameter and 12 inches in thickness). However, this technique is not often space efficient and does not offer the degree of cooling that could be provided by a more effective system of fluid circulation about the coils.
It would therefore be advantageous to provide an improved technique for cooling electromagnet coils, such as an improved spacer that is capable of effectively cooling the coils of a magnetized electromagnet. Also, it would be advantageous to provide a spacer that is capable of cooling the electromagnet coils with reduced current and power requirements. Finally, it would be advantageous to provide a spacer that effectively provides coolant to the electromagnet and that is easy to fabricate and install.